BUG: fix broken numpy.distutils Fortran handling

The `Path` and `COMMON_FIXED_EXTENSIONS` variables were not
defined at all. This code is untested, and SciPy doesn't build
with NumPy `main` before this fix. The issue was introduced
a few days ago in gh-22885.

numpy/distutils/ccompiler.py

@@ -5,6 +5,7 @@
 import time
 import subprocess
 from copy import copy
+from pathlib import Path
 from distutils import ccompiler
 from distutils.ccompiler import (
     compiler_class, gen_lib_options, get_default_compiler, new_compiler,
@@ -279,7 +280,8 @@ def CCompiler_compile(self, sources, output_dir=None, macros=None,
 
     if not sources:
         return []
-    from numpy.distutils.fcompiler import (FCompiler, is_f_file,
+    from numpy.distutils.fcompiler import (FCompiler,
+                                           FORTRAN_COMMON_FIXED_EXTENSIONS,
                                            has_f90_header)
     if isinstance(self, FCompiler):
         display = []
@@ -338,7 +340,7 @@ def single_compile(args):
                 if self.compiler_type=='absoft':
                     obj = cyg2win32(obj)
                     src = cyg2win32(src)
-                if Path(src).suffix.lower() in COMMON_FIXED_EXTENSIONS \
+                if Path(src).suffix.lower() in FORTRAN_COMMON_FIXED_EXTENSIONS \
                    and not has_f90_header(src):
                     f77_objects.append((obj, (src, ext)))
                 else:

numpy/distutils/fcompiler/__init__.py

@@ -19,6 +19,7 @@
 import os
 import sys
 import re
+from pathlib import Path
 
 from distutils.sysconfig import get_python_lib
 from distutils.fancy_getopt import FancyGetopt
@@ -37,6 +38,10 @@
 
 __metaclass__ = type
 
+
+FORTRAN_COMMON_FIXED_EXTENSIONS = ['.for', '.ftn', '.f77', '.f']
+
+
 class CompilerNotFound(Exception):
     pass
 
@@ -571,7 +576,7 @@ def dump_properties(self):
     def _compile(self, obj, src, ext, cc_args, extra_postargs, pp_opts):
         """Compile 'src' to product 'obj'."""
         src_flags = {}
-        if Path(src).suffix.lower() in COMMON_FIXED_EXTENSIONS \
+        if Path(src).suffix.lower() in FORTRAN_COMMON_FIXED_EXTENSIONS \
            and not has_f90_header(src):
             flavor = ':f77'
             compiler = self.compiler_f77
@@ -971,7 +976,6 @@ def dummy_fortran_file():
     return name[:-2]
 
 
-is_f_file = re.compile(r'.*\.(for|ftn|f77|f)\Z', re.I).match
 _has_f_header = re.compile(r'-\*-\s*fortran\s*-\*-', re.I).search
 _has_f90_header = re.compile(r'-\*-\s*f90\s*-\*-', re.I).search
 _has_fix_header = re.compile(r'-\*-\s*fix\s*-\*-', re.I).search